Motor-operated circuit breaker

ABSTRACT

An electric circuit breaker is manually operable by means of a front accessible handle and electrically operable by means of an improved motor-operating mechanism having resilient handleoperating means for preventing damage to the circuit breaker handle during operation.

United States Patent Alfred E. Maier;

Louis N. Ricci, both of Beaver Falls; Charles E. llaugh, New Brighton, all of Pa. [2 1] Appl. No. 23,199

[72] inventors [22] Filed Mar. 27, 1970 [45] Patented Dec. 21, 1971 [73] Assignee Westinghouse Electric Corporation Pittsburgh, Pa.

[54] MOTOR-OPERATED CIRCUIT BREAKER 9 Claims, 6 Drawing Figs.

[52] [1.8. CI 335/69 [51] int. Cl "01h 3/02 [50] Field oiSearch 335/69,68, 7|

[56] References Cited UNITED STATES PATENTS 3,171,920 3/1965 Klein ct a1.. 335/69 3,198,907 8/1965 Archer et al.. 335/69 3,296,565 1/1967 Kiesel et al. 335/71 Primary Examiner-Harold Broome Attorneys-A. T. Stratton, Clement L. McHale and W. A.

Elchik ABSTRACT: An electric circuit breaker is manually operable by means of a front accessible handle and electrically operable by means of an improved motor-operating mechanism having resilient handle-operating means for preventing damage to the circuit breaker handle during operation.

PATENIEB [15:21 am SHEET 3 [IF 3 FIGS.

MOTOR-PERATED crRcurr BREAKER CROSS-REFERENCE TO RELATED APPLICATION Certain parts herein disclosed are disclosed and claimed in the copending patent application of A. J. Hendry et al. titled Motor Operated Circuit Breaker Control," Ser. No. 23,198, filed concurrently herewith.

BACKGROUND OF THE INVENTION 1. Field of the Invention Motor operated circuit breakers.

2. Description of the Prior Art In the patent to Staak, US. Pat. No. 3,198,908, there is disclosed a motor-operated circuit breaker comprising a circuit breaker and a motor-operating mechanism supported on the front of the circuit breaker with the handle structure of the circuit breaker protruding frontward to enable manual opera tion of the circuit breaker. The handle structure is operated by means of a traveling nut that is driven by a driving screw that is connected to the motor shaft, and the motor shaft is mounted for limited resilient longitudinal movement for absorbing the inertia energy of the moving parts in order to prevent damage to the handle structure.

SUMMARY OF THE INVENTION A motor-operated circuit breaker comprises an insulatinghousing-type circuit breaker and an enclosed motor-operating mechanism supported at the front of the circuit breaker with the handle structure of the circuit breaker protruding frontward to enable manual operation of the circuit breaker. The motor-operating mechanism comprises a reversible motor having a driving screw member connected to the output shaft thereof for driving a traveling nut supported on the screw member. An operating structure, that is connected to move with the traveling nut, comprises resiliently movable connecting means connected to the handle structure. Ball bearing means is connected between the traveling nut and screw member to reduce friction during motor and manual operations. The reversible motor is electrically operable to rotate the screw member in two different directions to reciprocate the traveling nut and operating structure to thereby drive the handle structure between open and closed operating positions. The motor-operating mechanism is an enclosed unit, and a sliding shield is supported at the internal front of the motoroperating mechanism enclosure for substantially closing the opening through which the handle structure extends in all positions of the handle structure. The motor is fixedly supported in the enclosure, and the end of the screw member is supported by a ball bearing mounted on one end wall of the enclosure. Rollers are used to transmit the force between the operating structure and the handle structure to reduce friction between the parts. A slot-and-pin connection is used between the motor shaft and the screw member to transmit torque between the parts while permitting the parts to be slightly out of alignment due to manufacturing tolerances.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side sectional view of a motor-operated circuit breaker with parts broken away and with parts shown in elevation for the purpose of clarity, and with the section illustrating the center pole unit of a three-pole circuit breaker;

FIG. 2 is a plan view of the motor-operated circuit breaker of FIG. 1 with the cover of the motor-operating mechanism enclosure removed;

FIG. 3 is a side sectional view on one of the limit-switch circuit breakers seen in FIG. 2;

FIG. 4 is a sectional view, with parts broken away, illustrating part of the motor-operating mechanism with different parts of the mechanism shown in broken lines to illustrate positions reached during operation of the mechanism;

FIG. 5 is an elevational view of the connecting pin between the motor shaft structure and the driving screw member; and

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, there is shown, in FIGS. 1 and 2, a motor-operated circuit breaker 5 comprising a circuit breaker 7 and a motor-operating mechanism 9.

The circuit breaker 7 is an insulating-housing-type threepole circuit breaker that is more specifically described in the patent to Albert R. Cellerini et al. US. Pat. No. 3,287,534, patented Nov. 22, 1966. Thus, only a brief description of the circuit breaker 7 is provided herein. The circuit 7 comprises an insulating housing IlQhaving an opening 13 at the front thereof, and a circuit-breaker structure 15 supported in the housing 11 with a handle 17 protruding through the opening 13 to enable operation of the circuit breaker. An extension 19 is secured to the handle 17 to provide a handle structure 21 that is operated by the motor-operating mechanism in a manner to be hereinafter described.

Each pole of the three-pole circuit breaker comprises a conductor 23, a stationary contact 25 and a movable contact 27 secured to a movable contact arm 29 that is mounted on a switch arm 31 that is supported for movement about a pivot 33. Each movable contact arm 29 is connected to conducting means 35 by means of a flexible conductor 36. Each conducting means 35 extends through a trip device 37 that is automatically operable to trip the circuit breaker to the open position in response to an overload in any of the three pole units. The switch arm 31 for the center pole unit is pivotally connected to a toggle link 39 that is in turn pivotally connected to a toggle link 41 that is pivotally connected to a releasable trip member 43. The trip member 43 is pivotally mounted on a pin 45 at one end thereof and latched by means of a latch means 47 at the other end thereof. Overcenter tension spring means 49 is connected at the lower end thereof to the knee pivot 51 of the toggle 39, 41 and at the upper end thereof to the bight portion of an inverted generally U-shaped operating lever 53 that is mounted for pivotal movement on pin means 55. The operating lever 53 is connected to handle structure 21 for operation between open and, closed positions.

The circuit breaker 7 is shown in the closed position in FIG. 1. The circuit breaker is operated to the open position by movement of the handle structure 21 about the pivot 55 in a counterclockwise direction from the closed position seen in FIG. 1 to either the open position or the reset position during which movement the spring means 49 is carried overcenter to cause collapse of the toggle 39, 41 and opening movement of all three of the switch arms 31 which are tied together for simultaneous movement by means of a common tie bar 59. The circuit breaker is closed by movement of the handle structure 21 in a clockwise direction to the closed position seen in FIG. I during which movement the overcenter spring means 49 is moved to erect the toggle 39, 41 to simultaneously pivot the switch arm 31 about the pivots 33 to the closed position shown in FIG. 1.

Upon the occurrence of an overload in any of the three pole units, the circuit breaker is tripped open by operation of the trip device 37 which releases the latch 47 to effect automatic release of the latched trip member 43. Upon release of the trip member 43, the overcenter spring means 49 moves the trip member 43 in a clockwise direction to change the line of action of the overcenter spring means 49 and cause collapse of the toggle 39, 41 to simultaneously open the three switch arms 31. The circuit breaker is trip free in that the parts will trip open with the handle structure 21 being held in the closed position due to friction in the motor-operating mechanism. Following a tripping operation, the circuit breaker can again be operated only after the releasable trip member 43 is operated to the reset and relatched position. The circuit breaker is reset by movement of the handle structure 21 in a counterclockwise direction to the reset position which is a position past the full off or open position. During this movement, a pin means 60 on the operating lever 53 engages a surface 61 on the releasable trip member 43 to move the trip member 43 in a counterclockwise direction about the pivot 45, and near the end of this movement the releasable trip member 43 is relatched by the latch means 47 in the manner described in the above-mentioned US. Pat. No. 3,287,534.

The motor-operating mechanism 9 comprises an enclosure 62 and a mechanism 63 supported within the enclosure 62. The enclosure 62 comprises a receptacle part 64, having an opening 65 in the base thereof for receiving the handle structure 21, and a cover 66 supported on the receptacle part 64. The cover 66 has an opening 67 therein for receiving the handle structure 21. A slider 68, is supported on the inside of the cover 66 for generally rectilinear reciprocal movement to move with the handle structure 21. The handle structure 21 protrudes through an opening 69 in the slider 68, and the slider 68 substantially closes the opening 67 in the cover 66 in all positions of the handle structure 21.

The mechanism 67 comprises a motor drive structure 70; a pair of circuit breakers A and B; a pair of relays X and Y all supported in the receptacle part 64 of the enclosure 62. The enclosure 62 of the motor-operating mechanism 9 is suitably mounted on the front of the insulating housing 7 with the handle structure 21 protruding through the front of the enclosure 62 as shown in FIG. 1.

The motor drive structure 70 comprises a reversible electric motor 75 having an output shaft 77. The motor 75 is fixedly secured to a bracket 79 that is secured to the base of the receptacle part 64 of the enclosure 62. A pair of guide rods 81 and 83 are fixedly secured at one end thereof to the bracket 79 and at the other end thereof to a plate member 85 that is secured to the end wall of the receptacle 64 by securing screw means 87. The guide rods 81, 83 extend through openings in the plate 85 as shown in FIG. 1. As can be seen in FIG. 1, an elongated extension shaft 91 is connected to the output shaft 77 of the motor 75 by means of a pin 93 (FIG. having a large-diameter part 95 that fits through an opening in the shaft 77 and small-diameter endparts 97 that fit in a pair of slots (FIG. 1) in the extension shaft 91. The slot-and-pin connection between the output shaft 77 and the extension shaft 91 provides a fit that enables the output shaft 77 to rotate the extension shaft 91 while permitting the shafts 77, 91 to be slightly out of alignment due to manufacturing tolerances. Another pin 93 (FIG. 4) similarly connects the extension shaft 91 with a drive screw member 97 so that rotation of the extension shaft 91 will rotate the drive screw member 97 while permitting the parts to be slightly out of alignment due to manufacturing tolerances. One end of the drive screw member 97 is connected to the extension shaft 91 by means of the pin 93 and the other end (FIGS. 1 and 2) of the drive screw member 97 extends through an opening in the plate 85 and is supported on the inner raceway of a ball bearing member 99 that is supported on the end wall of the receptacle 64 by means of the supporting plate 85. The bearing member 99 supports the drive screw member 97 against radial movement and also against elongated thrust movement during operation of the motor-operating mechanism. A traveling nut 101, having an internal threaded part (FIG. 4), is supported on the external threaded part of the drive screw member 97 for axial or longitudinal movement on the screw member 97. As can be seen in FIG. 4, the traveling nut 101 is supported on the screw member 97, and a plurality of ball bearings 103 are disposed in the threaded portion between the nut 101 and screw member 97 to reduce friction between these parts during operation of the motor-operated circuit breaker 5. The traveling nut 101 comprises a channel part 105 to enable the ball bearings 103 to move through the channel part 105 as they are displaced from the threaded portion when the traveling nut 101 moves on the drive screw member 97. As can be seen in FIG. 4, the traveling nut 101 comprises an externally threaded extension part 107 that is threaded into an internally threaded tube 109 to secure the traveling nut 101 and tube 109 together for unitary movement. As can be seen in FIG. 2, an operating structure 113 comprises a generally U-shaped plate member 115 and a pair of generally U-shaped plate members 117 that are fixedly secured to the opposite legs of the generally U- shaped member 115 to form a movable carriage 118. The carriage 118 is provided with openings in the opposite end walls thereof for receiving the guide rods 81, 83 (FIGS. 1 and 2) which guide the carriage 118 during operation of the motoroperated circuit breaker. As can be seen in FIG. 4, a flat spring support or plate member 119 is provided with an opening therein for receiving the tubular member 109 and a pair of openings therein for receiving the guide rods 81, 83 (FIG. 1). Another flat spring support or plate member 120 is provided adjacent the other end wall of the carriage 118. The plate member 120 has an opening therein for receiving the tubular member 109 and a pair of openings therein for receiving the guide rods 81, 83 (FIG. 1). A pair of coil compression springs 121 and 123 (FIGS. 1 and 2) are supported on the guide rods 81, 83 respectively to bias the plates 119, 120 apart into engagement with the opposite stop parts or end walls of the carriage or frame 118. As can be seen in FIG. 4, the traveling nut 101 comprises shoulder means 127 that engage the plate 119 to move the plate 119 to the right upon movement of the traveling nut 101 to the right. A collar member 129 is provided on the tubular member 109 to provide a shoulder portion that engages the plate 120 (FIG. 4) to move the plate 120 to the left upon movement of the traveling nut 101 to the left.

As can be seen in FIG. 2, the bight portions of the U-shaped plates 1 17 provide sidewalls or side plates of the carriage 118 that support a pair of roller members 131, that are supported for rotational movement on the plate parts 117 of the carriage 118. The rollers 131, 135 straddle the handle operator 21 so that upon movement of the carriage 118 the rollers 131, 135 will drive the handle structure 21 and so that upon manual movement of the handle structure 21 the carriage 118 will be operated.

The circuit breaker 7 is shown in the closed position in FIGS. 1 and 2. When it is desired to electrically operate the circuit breaker 7 to open the breaker 7, the reversible motor 75 is energized in a manner to be hereinafter described. Upon energization of the reversible motor. 75 the output shaft 77 is rotated to rotate the intermediate shaft 91 to thereby rotate the drive screw member 97. Upon rotation of the drive screw member 97, the traveling nut 101 is driven to the left (FIGS. 1 and 2). As the traveling nut 101 moves to the left, the tubular member 109, that is fixed to the traveling nut 101, moves to the left and moving the shoulder part 129 (FIG. 4) to the left to move the plate 120 to the left. The compression springs 121, 123 are precharged sufficiently to immediately start moving the handle structure 21, in a manner to be hereinafter described, upon movement of the plate 120 to the left. Upon movement of the plate 120 to the left, the plate 120 pushes against the precharged springs 121, 123, to push the plate 119 to the left and the plate 119, pushing against the end wall part of the carriage 118, pushes the carriage 118 to the left. Upon movement of the carriage 118 to the left, the roller 135 moves the handle structure 21 from the closed position seen in FIG. 1 to the reset position hereinbefore described. When the carriage 118 and handle structure 21 reach the reset position the parts are stopped in a manner to be hereinafter described. With the handle structure 21 in the open position, the circuit breaker is electrically operated to the closed position by energization of the reversible motor 75 in a manner to be hereinafter described. Closing energization of the reversible motor 75 rotates the output shaft 77, extension shaft 91 and drive screw member 97 in the opposite direction to move the traveling nut 101 to the right. Upon movement of the traveling nut 101 to the right, the plate 119, which is engaged by the shoulder 127 (FIG. 4) of the traveling nut 101, is moved to the right to push against the precharged springs 121, 123 to thereby push the plate 120 to the right, and the plate 120, pushing against the other end wall of the carriage 118, moves the carriage 118 to the right. During this movement, the roller 131 moves the handle structure 21 to the closed position seen in FIG. 1, and at the end of this movement the parts are braked to a stop in a manner to be hereinafter described.

With the motor 75 deenergized, the circuit breaker can be manually operated between the open and closed positions by manual movement of the handle structure 21 between the open and closed positions. During this movement, the rollers 131, 135 are manually moved to operate the carriage 118 and traveling nut 101, with the drive screw member 97, extension shaft 91 and output shaft 77 being rotated as the traveling nut 101 moves during manual operation. The ball-bearing connection between the traveling nut 101 and drive screw member 97 reduces the friction so that the manual operation can be performed without disconnecting the handle structure 21 from the motor operating mechanism.

During electrical operations, the carriage 118 is motor driven, and at the end of the operating movement of the handle structure 21, the motor driven parts may move a limited amount after the handle structure reaches the operating positions before the motor driven parts are braked to a complete stop. It is desirable to provide a resilient connection between the traveling nut 101 and the handle structure 21 so that this additional limited movement can occur without breaking the handle structure 21. Movement of the handle structure 21 is limited in both directions by the housing of the circuit breaker 7 around the opening 13 (FIG. 1). As can be seen in FIG. 4, when the carriage 118 is moved to the right to close the circuit breaker, the traveling nut 101 moves slightly past the limit position of the handle structure 21 moving the plate 119 to the right (to the position shown in broken lines) additionally charging the precharged springs 121 and 123 without applying damaging forces to the handle structure 21. The plate 119 reaches this position only temporarily since the force of the precharged springs 121, 123 will move the plate 119 and nut 101 back to the position where the plate 119 engages the one end wall of the carriage 118 after the inertia of the moving parts is taken up by the springs 121, 123. When the carriage 118 is moved to the left to open the breaker, the traveling nut 101 moves slightly past the limit position of the handle structure 21 moving the plate 120 to the left (to the position shown in broken lines in FIG. 4) additionally charging the precharged springs 121 and 123 without applying damaging forces to the handle structure 21. The plate 120 reaches this position only temporarily since the force of the precharged springs 121, 123 will move the plate 120 and nut 101 back to the position where the plate 120 engages the associated end wall of the carriage 118 after the inertia of the moving parts is taken up by the springs 121,123.

The springs 121, 123, which provide the resilient connection between the traveling nut 101 and handle structure 21, are precharged sufficiently so that they will immediately start moving the handle structure 21 upon movement of the traveling nut 101. The springs 121, 123, however are not so precharged that they will cause breakage of the handle operator 21 during electrical operations of the motor-operated circuit breaker 5. Each of the limit switch circuit breakers A and B is of the type more specifically described in the U.S. Pat. No. 2,624,816, patented June 6, 1953. Thus, only a brief description of the circuit breakers A and B, which are of identical construction, is herein provided. Referring to FIG. 3, the circuit breaker A comprises an insulating housing 139'having an opening 141 in the front thereof. A circuit breaker mechanism 143, supported in the housing 139, comprises an operating handle 145 that protrudes through the opening 141. The circuit breaker mechanism 143 comprises a stationary contact 147 and a movable contact 149 that is mounted on the lower end of a contact arm 151. The contact arm 151 is a generally U-shaped member that pivotally engages an insulating operating lever 153 that is formed integral with the handle 145 and that is pivotally supported, at 155, on the sidewalls of the insulating housing 139. A tension spring 157 is connected at the lower end thereof to the bight portion of the contact arm 151, and at the upper end thereof to a releasable trip member 159 that is latched at one end thereof and pivotally supported on a pin 161 at the other end thereof. The releasable trip member 159 is latched by means of a trip device 163. The circuit breaker A is manually operated to the open position by clockwise movement of the handle to move the contact arm 151 and spring 157 to an overcenter position wherein the spring 157 snaps the contact arm 151 to the open position. The circuit breaker is manually closed by counterclockwise movement of the handle 145 to the position seen in FIG. 3 to move the contact arm 151 and spring 157 to an overcenter position wherein the spring 157 snaps the contact arm 151 to the closed position seen in FIG. 3. The circuit breaker A is tripped open automatically upon the occurrence of an overload current above a predetermined value by operation of the trip device 163 which moves to the right to release the trip member 159. Upon release of the trip member 159 the spring 157 pivots the trip member 159 in a clockwise direction about the pivot 161 to cause opening movement of the contact arm 151 in a well-known manner. Following a tripping operation, the circuit breaker is reset and relatched by movement of the operating handle 145 to a position slightly past the full open or off position during which movement the member 153 engages a pin 165 on the trip member 159 to pivot the trip member 159 in a counterclockwise direction to a position wherein the trip member 159 is relatched by means of the trip device 163. Thereafter, the circuit breaker A can be manually operated in the same manner as was hereinbefore described. Reference is made to the above-mentioned patent to Bigenheimer, U.S. Pat. No. 2,624,816 for a more complete description of the construction and operation of the circuit breakers A and B.

Referring to FIG. 2, it will be noted that a plate member 169 is fixedly secured to the carriage 118, and a pair of drive rods 171, 173 extend through openings in the plate 169. A pair of springs 175, 177 are supported on the rods 171, 173 between the plate 169 and a pair of nuts 179, 181 on the outer ends of the rods. 171, 173 respectively. Another pair of springs 185, 187 are mounted on the rods 171, 173 and supported between the plate 169 and a pair of nuts 189, 191 respectively that are secured to the rods 171, 173, respectively. A pair of generally U-shaped brackets 195, 197 are threadedly mounted on the ends of the rods 171, 173 and locked in position by a pair of nuts 201, 203 respectively. Each of the brackets 195, 197 is connected to the associated operating handle 145 of the associated circuit breaker by means of a pin that extends through an opening in the associated handle 145, and is secured to the opposite legs of the associated bracket. As shown in FIG. 2, the handle 145 of the circuit breaker A is in the open position and the handle 145 of the circuit breaker B is in the closed position. The circuit breakers A and B are supported in reverse positions from each other so that movement to the left of the rods 171, 173 will move the circuit breaker A to the closed position and the circuit breaker B to the open position. Movement to the right of the rods 171, 173 will move the circuit breaker A to the open position and the circuit breaker B to the closed position. The springs 175, 177, 185 and 187 provide resilient connections between the plate 169 and the circuit breaker handles 145 to prevent damage to the circuit breaker handles 145 during operation of the motoroperated circuit breaker 5. The nuts 179, 181, 189, 191 can be loosened and threadedly adjusted on the rods 171, 173 to provide adjustment for proper operation of the circuit breakers A and B during operation of the motor-operated circuit breaker 5. The limit switch circuit breaker B is adjusted to go to its closed position just before the handle structure 21 9 reaches its closed position. The limit switch circuit breaker A should go to its open position just before the handle structure 21 reaches its closed position. The limit switch circuit breaker A should go to its closed position just before the handle structure 21 goes to its open position. The limit switch circuit breaker B should go to its open position just before the handle structure 21 goes to its reset position. When the handle structure 21 is electrically operated to open the breaker, the handle structure 21 is driven to the limit by the inertia of the moving parts so that the handle structure always goes to the reset position during electrical opening operations. When the handle structure 21 is manually operated to open the breaker however, the handle structure 21 will stop in the open position unless the operator makes a special effort to drive the handle structure to the reset position. With the above-mentioned adjustments of the circuit breakers A and B, both of the breakers A and B are closed following a manual operation to the open position. Thus, following a manual opening operation, an operator can electrically operate the handle structure to either the reset or closed position merely by pushing the selected pushbutton FBI or PB2 (FIG. 6). After the adjustments of the circuit breakers A and B are made, the nuts 179, 181, 189, 191 are locked in place with a suitable cement.

Each of the relays X and Y is a four-pole electromagnetic relay of the type more specifically described in the patent to G. Jakel, US. Pat. No. 3,088,058 patented Apr. 30, 1963.

The electric control for operating the circuit breaker 7 is shown schematically in FIG. 6. As can be understood with reference to FIG. 6, the lines LI and L2 are connectable to a suitable power source for energizing the motor 75 to operate to the circuit breaker 7. The parts are shown in FIG. 6 with the circuit breaker 7 in the open position and the relays X and Y in the deenergized condition. Two pushbutton switches P81 and PB2, which may be mounted on the cover 66 (FIG. 1) for external operation, are momentary pushbuttons which automatically return to the open position upon release thereof by the operator. As can be seen in FIG. 6, with the circuit breaker 7 open, the circuit breaker A is closed and the circuit breaker B is open. With the X relay deenergized the X relay contacts X1 and X2 are normally open and the X relay contacts X3 and X4 are normally closed. With the Y relay deenergized, the Y relay contacts Y1 and Y2 are normally open and the Y relay contacts Y3 and Y4 are normally closed. The pushbutton PBl is manually closed momentarily to electrically open the circuit breaker 7. Upon closing of the pushbutton PBl the X relay coil XC is energized from the line L1 through the push button PB1, the circuit breaker A, the normally closed Y relay contact Y3, the X relay coil XC to the line L2. Upon energization of the, X relay coil XC the relay picks up closing the contacts X1 and X2, and opening the contacts X3 and X4. Upon closing of the contacts X1, a seal-in circuit is established from the line L1 through the contact X1, the circuit breaker A, the contact Y3, the relay coil XC to the line L2 so that upon release of the pushbutton PBl the relay coil XC will remain energized until the circuit breaker A is opened. With the relay coil XC energized, a winding of the reversible motor 75 is energized through the contact X2. This circuit is established from the line Ll through the relay contact X1, the circuit breaker A, the relay contact X2, the winding of the motor 75 to the line L2. With the reversible motor 75 energized, the motor drive structure is operated to move the handle structure 21 of the circuit breaker 7 to the closed position to close the contacts 25, 27 of the circuit breaker in the same manner as was hereinbefore described. Just before the handle structure 21 reaches the closed position, the circuit breaker B is operated to its closed position and the circuit breaker A is operated to its open position. The contacts X3 and Y3 of the relays X and Y operate as an electrical interlock to prevent simultaneous energization of the relay coils XC and YC. Just before the handle structure 21 reaches the closed position the motor circuit 75 is interrupted through the contacts of the circuit breaker A. This is the circuit from the line L1 through the relay contact X1, the circuit breaker A, the relay contact X2, the winding of the motor 75 to the line L2. Opening of the circuit breaker A also opens the seal-in circuit from the line L1 through the contact X1, the circuit breaker A, the contact Y3, the coil XC to the line L2 to thereby deenergize the coil XC and drop out the relay X opening the contacts X1 and X2 and closing the contacts X3 and X4. By using the circuit breaker A to open the motor current, the contacts of the X relay are protected allowing the use of a smaller and lower cost relay par ticularly for DC operation. When the X relay drops out closing the contacts X4, a direct short circuit is established from the line L2 through the motor winding, the contact X4, the contact Y4 to the line L2 to provide dynamic braking which brakes the motor, and the parts operated by the motor, to a stopped condition.

With the circuit breaker 7 closed, the motor 75 deenergized, the relay coils XC and YC deenergized, the circuit breaker A opened and the circuit breaker B closed, the motoroperated circuit breaker 5 is electrically operated to the open position by momentary closing of the pushbutton contact PB2. Closing of the contact PB2 energizes the Y relay coil from the line L1 through the contact PB2, the closed circuit breaker B, the contact X3, the Y relay coil YC, to the line L2. Upon energization of the coil YC, the Y relay picks up closing the normally open contacts Y1 and Y2, and opening the normally closed contacts Y3 and Y4. Upon closing of the contact Y], a seal-in circuit is established from the line L1 through the contact Y1, the circuit breaker B, the contact X3, the relay coil YC to line L2 sealing in the picked up Y relay which will remain energized upon release of the momentary pushbutton PB2 until the circuit breaker B is opened. When the Y relay is picked up, a circuit is established energizing another winding of the reversible motor 75 from the line L1 through the contact Y1, the circuit breaker B, the contact Y2, the winding of the motor 75, to the line L2 energizing the reversible motor 75 to operate the motor-operated circuit breaker 5 from the closed position to the open position in the manner hereinbefore described. Just before the handle structure 21 reaches the open position, the circuit breaker A will be operated to its closed position; and the circuit breaker B will be operated to its open position just before .the handle structure reaches its reset position. As was hereinbefore described, the contacts X3, Y3 prevent simultaneous energization of the relay coils XC and YC. When the circuit breaker B opens, the energizing circuit for the motor 75 is interrupted through the contacts of the circuit breaker B which also open the seal-in circuit to deenergize the relay coil YC. By interrupting the motor circuit with the circuit breaker B, the contacts of the Y relay are protected allowing the use of a smaller and a lower cost relay particularly for DC operation. When the seal-in circuit through the contact Y2 is interrupted the relay coil YC is deenergized and the Y relay drops out closing the contact Y4 to establish a short circuit from the line L2, through the motor winding, the contact X4, the contact Y4, to the line L2 to dynamically brake the motor 75 to bring the motor and the parts driven by the motor to a stopped condition.

If an automatic reset is desirable, an auxiliary switch can be operated to automatically reset the circuit breaker 7 by means of the motor drive structure 63 following a tripping operation of the circuit breaker 7. A well-known type of auxiliary switch can be mounted inside the circuit breaker in a normally open position to be automatically closed by movement of the trip member 43 (FIG. 1) to the tripped position and automatically opened when the trip member 43 is moved to the relatched reset position. The contacts of the automatic reset switch are wired to bypass the pushbutton PB2 as shown at AR in FIG. 6. When the automatic reset is utilized the contact AR will be automatically closed by movement of the trip member 43 (FIG. 1) to the tripped position. Closing of the contact AR will energize the reversible motor 75 in the manner hereinbefore described to automatically provide an electrical operation of the handle operator 21, (FIG. 1) to the reset position, and when the handle operator 21 reaches the reset position the circuit breaker B will be opened to interrupt the motor current and to drop out the Y relay in the manner hereinbefore described with the automatic reset contact AR being opened by movement of the trip member 43 to the reset position.

We claim as our invention:

1. A motor-operating mechanism for operating a circuit breaker comprising a pair of contacts and having a handle structure movable between first and second positions to open and close said contacts,

said motor-operating mechanism comprising "a reversible motor comprising an output shaft rotatable upon energization of said motor, an elongated drive screw, connecting means operatively connecting said drive screw with said output shaft, a traveling nut on said drive screw intermediate the ends of said drive screw, a carriage structure connected to be moved by the movement of said traveling nut, said carriage structure comprising a pair of stop parts movable unitarily with said carriage structure, a pair of movable spring support members between said stop parts, spring means between said spring support members biasing said spring support members in opposite directions into engagement with said stop parts, connecting means on said carriage structure for connecting said carriage structure with said handle structure, said reversible motor being electrically operable to rotate said drive screw in two different directions to reciprocate said traveling nut and said carriage structure to thereby reciprocate said handle structure between said first and 7 second positions,

upon operation of said motor-operating mechanism to move said handle structure to the first of said positions said traveling nut moving a first of said spring support members to operate through said spring means the second of said spring support members and the second of said stop parts to move said carriage structure to thereby move said handle structure to said first position, and upon operation of said motor operating mechanism to move said handle structure to the second of said positions said traveling nut moving the second of said spring support members to operate through said spring means the first of said spring support members and the first of said stop parts to move said carriage structure to thereby move said handle structure to said second position.

2. A circuit breaker according to claim 1, and a pair of roller members rotatably mounted on said carriage structure straddling said handle structure to move said handle structure upon operation of said motor-operating mechanism.

3. A motor-operating mechanism according to claim 2, a pair of elongated stationary guide rods, said carriage structure being mounted on said guide rods for longitudinal reciprocal movement, and said spring means comprising a pair of coil compression springs on said pair of guide rods biasing said pair of spring support members toward said stop parts of said carriage structure.

4. A circuit breaker according to claim 1, and said connecting means between said output shaft and said drive screw comprising a slot-and-pin connecting means to transfer rotational movement of said output shaft to said drive screw without requiring said drive screw to be in fixed alignment with said output shaft.

5. A motor-operating mechanism according to claim 1, said motor-operating mechanism comprising support means, said motor being fixedly mounted on said support means, said output shaft being connected to one end of said drive screw, and bearing means supported on said support means supporting the other end of said drive screw.

6. in combination, a circuit breaker comprising a housing having an opening in the front thereof, a circuit breaker structure supported in said housing and comprising a pair of contacts, a handle structure extending through said opening in said housing and being movable between first and second positions to open and close said contacts,

a motor-operating mechanism supported on the front of said circuit breaker housing, said motor-operating mechanism comprising an enclosure and a motor-operating structure supported in said enclosure, said enclosure having an opening in the back thereof and an opening in the front thereof, said handle structure extending through said openings in the back and front of said enclosure, said motor-operating structure comprising a reversible motor having an output shaft, an elongated drive screw operatively connected to said output shaft, a traveling nut on said drive screw, an operating structure connected to move with said traveling nut, said operating structure comprising resiliently movable means providing a resilient connection between said traveling nut and said handle structure, said reversible motor being electrically operable to rotate said drive screw in two different directions to reciprocate said traveling nut and said operating structure to thereby move said handle structure between said first and second positions,

said handle structure extending frontward through said opening in the front of said enclosure and being manually operable to open and close said contacts during which manual operations said handle structure said operating structure said traveling nut said drive screw and said output shaft are moved without requiring a disconnection between said handle structure and said motor-operating mechanism.

7. A combination according to claim 6, a ball bearing connection between said traveling nut and said drive screw to reduce friction between said traveling nut and said drive screw, said reversible motor being fixedly mounted on said enclosure, said drive screw being operatively connected to said output shaft at one end thereof, and bearing support means supported on said enclosure and supporting the other end of said drive screw for rotational movement.

8. A motor-operating mechanism according to claim 6, said operating structure comprising a carriage supported for reciprocal movement, said carriage comprising a pair of end wall parts and a pair of sidewall parts, a pair of plate members supported adjacent said end wall parts, spring means biasing said plate members away from each other toward said end wall parts, means on said carriage connected to said handle structure, upon operation of said reversible motor in a first direction to open said contacts said traveling nut operating to move a first of said plate members which operates through said spring means to bias the second of said plate members against the second of said end wall parts to move said carriage structure to thereby move said handle structure to open said contacts, upon operation of said reversible motor in a second direction to close said contacts said traveling nut operating to move the second of said plate members which operates through said spring means to bias the first of said plate members against the first of said end wall parts to move said carriage structure to thereby move said handle structure to close contacts, and said spring means being precharged to start movement of said handle structure upon movement of said traveling nut without being precharged to such a condition as to break said handle structure when said handle structure reaches the operating positions thereof.

9. A combination according to claim 8, a pair of guide rods stationarily mounted in said enclosure, said carriage structure being supported on said guide rods for longitudinal movement, said spring means comprising a pair of compression springs on said guide rods biasing said pair of plate members toward said end wall parts of said carriage, and said means on said carriage connected to said handle structure comprising a pair of rollers rotatably mounted on the sidewall parts of said carriage structure straddling said handle structure. 

1. A motor-operating mechanism for operating a circuit breaker comprising a pair of contacts and having a handle structure movable between first and second positions to open and close said contacts, said motor-operating mechanism comprising a reversible motor comprising an output shaft rotatable upon energization of said motor, an elongated drive screw, connecting means operatively connecting said drive screw with said output shaft, a traveling nut on said drive screw intermediate the ends of said drive screw, a carriage structure connected to be moved by the movement of said traveling nut, said carriage structure comprising a pair of stop parts movable unitarily with said carriage structure, a pair of movable spring supporT members between said stop parts, spring means between said spring support members biasing said spring support members in opposite directions into engagement with said stop parts, connecting means on said carriage structure for connecting said carriage structure with said handle structure, said reversible motor being electrically operable to rotate said drive screw in two different directions to reciprocate said traveling nut and said carriage structure to thereby reciprocate said handle structure between said first and second positions, upon operation of said motor-operating mechanism to move said handle structure to the first of said positions said traveling nut moving a first of said spring support members to operate through said spring means the second of said spring support members and the second of said stop parts to move said carriage structure to thereby move said handle structure to said first position, and upon operation of said motor operating mechanism to move said handle structure to the second of said positions said traveling nut moving the second of said spring support members to operate through said spring means the first of said spring support members and the first of said stop parts to move said carriage structure to thereby move said handle structure to said second position.
 2. A circuit breaker according to claim 1, and a pair of roller members rotatably mounted on said carriage structure straddling said handle structure to move said handle structure upon operation of said motor-operating mechanism.
 3. A motor-operating mechanism according to claim 2, a pair of elongated stationary guide rods, said carriage structure being mounted on said guide rods for longitudinal reciprocal movement, and said spring means comprising a pair of coil compression springs on said pair of guide rods biasing said pair of spring support members toward said stop parts of said carriage structure.
 4. A circuit breaker according to claim 1, and said connecting means between said output shaft and said drive screw comprising a slot-and-pin connecting means to transfer rotational movement of said output shaft to said drive screw without requiring said drive screw to be in fixed alignment with said output shaft.
 5. A motor-operating mechanism according to claim 1, said motor-operating mechanism comprising support means, said motor being fixedly mounted on said support means, said output shaft being connected to one end of said drive screw, and bearing means supported on said support means supporting the other end of said drive screw.
 6. In combination, a circuit breaker comprising a housing having an opening in the front thereof, a circuit breaker structure supported in said housing and comprising a pair of contacts, a handle structure extending through said opening in said housing and being movable between first and second positions to open and close said contacts, a motor-operating mechanism supported on the front of said circuit breaker housing, said motor-operating mechanism comprising an enclosure and a motor-operating structure supported in said enclosure, said enclosure having an opening in the back thereof and an opening in the front thereof, said handle structure extending through said openings in the back and front of said enclosure, said motor-operating structure comprising a reversible motor having an output shaft, an elongated drive screw operatively connected to said output shaft, a traveling nut on said drive screw, an operating structure connected to move with said traveling nut, said operating structure comprising resiliently movable means providing a resilient connection between said traveling nut and said handle structure, said reversible motor being electrically operable to rotate said drive screw in two different directions to reciprocate said traveling nut and said operating structure to thereby move said handle structure between said first and second positions, said handle structure extending frontward through said opening in The front of said enclosure and being manually operable to open and close said contacts during which manual operations said handle structure said operating structure said traveling nut said drive screw and said output shaft are moved without requiring a disconnection between said handle structure and said motor-operating mechanism.
 7. A combination according to claim 6, a ball bearing connection between said traveling nut and said drive screw to reduce friction between said traveling nut and said drive screw, said reversible motor being fixedly mounted on said enclosure, said drive screw being operatively connected to said output shaft at one end thereof, and bearing support means supported on said enclosure and supporting the other end of said drive screw for rotational movement.
 8. A motor-operating mechanism according to claim 6, said operating structure comprising a carriage supported for reciprocal movement, said carriage comprising a pair of end wall parts and a pair of sidewall parts, a pair of plate members supported adjacent said end wall parts, spring means biasing said plate members away from each other toward said end wall parts, means on said carriage connected to said handle structure, upon operation of said reversible motor in a first direction to open said contacts said traveling nut operating to move a first of said plate members which operates through said spring means to bias the second of said plate members against the second of said end wall parts to move said carriage structure to thereby move said handle structure to open said contacts, upon operation of said reversible motor in a second direction to close said contacts said traveling nut operating to move the second of said plate members which operates through said spring means to bias the first of said plate members against the first of said end wall parts to move said carriage structure to thereby move said handle structure to close contacts, and said spring means being precharged to start movement of said handle structure upon movement of said traveling nut without being precharged to such a condition as to break said handle structure when said handle structure reaches the operating positions thereof.
 9. A combination according to claim 8, a pair of guide rods stationarily mounted in said enclosure, said carriage structure being supported on said guide rods for longitudinal movement, said spring means comprising a pair of compression springs on said guide rods biasing said pair of plate members toward said end wall parts of said carriage, and said means on said carriage connected to said handle structure comprising a pair of rollers rotatably mounted on the sidewall parts of said carriage structure straddling said handle structure. 